The influence of strength and gender on defining psychophysical lift capacity

This study examined the influence of strength, gender, and lift weight on psychophysical lift capacity of 209 men and 181 women. Each subject lifted from three to eight boxes that ranged in weight from 22 to 143 pounds. Lift difficulty was rated with Borg's CR-10 psychophysical scale. Standard methods were used to measure isometric arm, shoulder, and torso strength. Power functions defined each subject's dynamic lift profile within their lift range. Multiple regression provided an equation with a function to estimate psychophysical lift difficulty from lift load, strength, and gender by weight load interaction (R = 0.81, SEE = 1.7). The regression equation provides a model for estimating psychophysical floor-to-knuckle height lift capacity of men and women who vary in strength. These data document that psychophysical lift capacity was not only a function of load weight, but also the gender and strength of the lifter.